I'm surprised that nobody mentioned these, but IMO the Shinko 705 is the best tire option by far for these bikes, unless needs go more towards dirt. They work great on pavement, with enough dry traction to bust off peg feelers (which I've done twice), enough wet traction to ride supra-legal speeds in hard rain (don't ask), wear as well as anything out there (apart from rock-hard Mitas and Heidenau jobbers), and even have a great ride. Oh, and they're about $150/set.
When I bought my bike this spring, the PO had a brand new 705 front unmounted that he gave me with the bike, as the tires that were on it were completely shot. I admit that I was prejudiced against the bargain-basement Shinko brand, and was thoroughly prepared to hate the tires. But, I had a new front, and since at that time I could get a matching rear for $85, I figured what the hell...if they suck I'll just pitch 'em and get something else, with little money lost. Well, imagine my surprise when not only do they not suck, they are excellent tires...and I'm super picky about tires. the only thing I cant' comment on is off-road performance compared to other 80/20 tires, as I'm not an accomplished off-road guy, and all non-full-knobbies are terrible off road to me. That said, I've ridden on a little two-track, and a little more gravel road type stuff, and I've had no issue, but limits there are mine, and not the tires.
The last time I checked (2 weeks ago) they're about $150/set shipped. You can't go wrong...I like them enough that if they were $275/set next time I needed tired, I'd still buy them - they aren't "good for the money" they're just good. And they happen to be dirt cheap.